1. Field of the Invention
The present invention relates to an electron emission display, and more particularly, to an electron emission element with a resistance layer and an electron emission display having such an electron emission element.
2. Description of the Related Art
Generally, electron emission elements are classified into those using hot cathodes as an electron emission source, and those using cold cathodes as the electron emission source. There are several types of cold cathode electron emission elements, including Field Emission Array (FEA) elements, Surface-Conduction Emission (SCE) elements, Metal-Insulator-Metal (MIM) elements, and Metal-Insulator-Semiconductor (MIS) elements.
The FEA element includes electron emission regions and cathode and gate electrodes that are driving electrodes. The electron emission regions are formed of a material having a relatively low work function or a relatively large aspect ratio, such as a carbonaceous material or a nanometer-size material, so that electrons can be effectively emitted when an electric field is applied to the electron emission region in a vacuum atmosphere.
A typical electron emission display using the FEA elements includes a first substrate on which electron emission regions and cathode and gate electrodes are disposed, and a second substrate on which phosphor layers and anode electrodes are disposed. The electron emission regions are electrically connected to the cathode electrodes, and the gate electrodes are disposed above the cathode electrodes with an insulating layer disposed therebetween.
With the above-described structure, when predetermined driving voltages are applied to the cathode and gate electrodes, electric fields are formed at the electron emission regions in pixel regions, which are defined by the overlapping regions between cathode and gate electrodes. If at a pixel region, the voltage difference between the cathode and gate electrodes is higher than a threshold value, electrons will be emitted from the electron emission regions. The emitted electrons are attracted by the anode electrodes, to which a high voltage is applied, colliding with the phosphor layers of the corresponding pixel regions, thereby exciting the phosphor layers.
When an unstable driving voltage is applied however, to the cathode or gate electrode, or there is a voltage drop due to an internal resistance of the cathode or gate electrode, or the electron emission regions and the driving electrodes are not precisely fabricated, there may be a intensity difference between the electric fields applied to the electron emission regions of the respective pixel regions.
Particularly, when the cathode electrodes are formed of a transparent conductive material, such as Indium Tin Oxide (ITO), in order to apply a rear surface light-exposing process during formation of the electron emission regions, the cathode electrodes have a resistance higher than that of the cathode electrodes formed of metal conductive materials.
The above-described intensity difference of electric fields between the pixel regions causes a difference in the amount of electron emissions between the pixel regions. This deteriorates the luminescence uniformity of the pixels and thus the quality of the display.